There are known various processes for moulding, by injection, permitting the production of objects having at least one thermoplastic resin based inner layer covered with a lining sheet of thermoplastic or textile material.
In particular, there is known a technique for injection-compression moulding and, in this case, in a mould of matching shape, there is held in place a sheet of thermoplastic, or textile, material, generally referred to as a "skin", which will form the outer face of the object. Then, into the partially open mould, thermoplastic resin is injected beneath the so-called "skin" to form the inner layer of the object. This layer will impart volume and stiffness to the object, as well as a certain measure of strength.
Given the characteristics of these moulding processes, the "skin" is thus integral with one of the faces of the inner layer of the object and extends beyond this surface to permit a complementary finishing step.
In this process, the object is re-processed manually by an operator, who will coat the peripheral portion of the projecting skin with glue, once a degreasing step has been carried out. Then, the operator will press the skin against the lower portion of the inner layer in order to "tuck in" the object. Finally, the excess portions of skin are cut off, also manually, in a third step.
Such an injection-compression moulding technique is of interest as it is possible to obtain remarkable aesthetic effects while, at the same time, using materials enabling an acceptable cost to be achieved.
However, it should be noted that the manual reprocessing steps of tucking in and cutting greatly increases the cost.
The object of the present invention is to provide a process for the manufacture of a multilayered object by moulding, the object having at least one thermoplastic resin based inner layer, covered with a lining sheet, of thermoplastic or textile material, which enables the aforementioned drawbacks to be overcome and which avoids, in particular, manual re-processing operations to finish the object by permitting automatic tucking in at the time of manufacture.
The process according to the present invention makes it possible, at the end of the stage of traditional manufacture of a multilayered object by moulding, to fold back the extending portion of the lining sheet beneath the object and, if applicable, to allow the excess material to be cut off.
A further object of the present invention is to provide a mould for manufacturing such a multilayered object permitting implementation of the manufacturing process according to the present invention, which makes use of means for avoiding subsequent manual re-processing of the multilayered object and, in the moulding stage, permits the automatic tucking in and/or peripheral cutting off of the excess lining sheet.
Another object of the present invention is to provide a process and a mould for manufacturing such a multilayered object that can be implemented during low pressure injection moulding or during injection-compression moulding.
Further objects and advantages of the present invention will emerge in the course of the following description which is only provided, however, for illustrative purposes and is not intended to limit the invention.